Personally, my favorite Origin would have to be the Dwarf Noble and Dwarf Commoner. Dragon Age is by far the only rpg that ever really convinced me to roll a dwarf and make the race exciting for me. Plus, my best playthrough was my Dwarf Commoner, which was a true rags to riches to sacrifice story.Most of my PCs are humans followed by elves though considering I really don't like playing as short, squat people. Plus the bulk of the LIs are humans save Zev, so human PCs seem more fitting. But Origin wise the dwarves have the best in my own humble opinion.
I'd say Human Noble is the most stereotypical fantasy Origin, so if you're going for something really basic then I'd go with that. It's also the only option for non-Mage humans. Human Mage has a nice touch for Hawke (namely Mage Hawke) in DA2. Elven Mage is probably the most insignificant and least impactful (though those bonus points in Willpower + Magic don't hurt at all).
I have a canon for each Origin though so its no biggie. My top 3 are Dwarf Commoner (Male), Human Noble (Female) and Human Mage (Male).